Gusset bag and spout-attached gusset bag

ABSTRACT

A gusset bag includes: a pair of flat surface portions facing each other; and a pair of side surface portions facing each other and folded inward of the gusset bag. A containing portion used to contain an object is formed using the flat surface portions and the side surface portions. The gusset bag has a side edge-sealing portion in which a side edge portion of a flat surface portion of the flat surface portions and a side edge portion of a side surface portion of the side surface portions are heat-sealed together, and a folded-back portion in which the entire side edge-sealing portion is folded back and affixed to the flat surface portion or the side surface portion that forms the containing portion. The peel strength of the folded-back portion is lower than the peel strength of the side edge-sealing portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part application of U.S. patent application Ser. No. 13/392,438, which is the National Stage of International Application No. PCT/JP2010/064501, filed Aug. 26, 2010, which claims priority on Japanese Patent Application No. 2009-195613, filed Aug. 26, 2009, Japanese Patent Application No. 2009-292065, filed Dec. 24, 2009, and Japanese Patent Application No. 2010-188480, filed Aug. 25, 2010, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a gusset bag and a spout-attached gusset bag.

BACKGROUND

Standing pouches and flat bottom-type gusset bags are used as package bags for liquid or semi-liquid contents such as a jelly drink. These package bags are contrived to secure a self-standing property. Particularly, as package bags for a jelly drink or the like, gusset bags are widely used that can easily independently stand using the weight of the contents and can easily push out the contents by squeezing the bags by a user's hand.

As a specific example of the gusset bag, for example, a spout-attached gusset bag (for example, Patent Documents 1 and 2) is known in which edge portions of a laminate film having a heat-sealable film adhered to one side thereof are heat-sealed together in a state where the laminate film is arranged into a cylindrical shape, the laminate film is gusset-folded so that the heat-sealed portion is positioned on the rear surface or the side surface, and an upper edge portion and a lower edge portion are heat-sealed so that the laminate film has a bag shape with a spout liquid-tightly attached to the upper edge portion. However, when the spout-attached gusset bag contains contents, the body portion may swell, whereby the appearance thereof may deteriorate.

Meanwhile, as shown in FIGS. 34 and 35, a spout-attached gusset bag 101 (for example, Patent Document 3) is known that includes a gusset bag 110 and a spout 120, the gusset bag 110 is formed of a pair of flat surface portions 111 facing each other and a pair of side surface portions 112 that connect the side edges of the flat surface portions 111 and are folded inward of the gusset bag 110, and the spout 120 is attached to the gusset bag 110 to discharge the contents from the gusset bag 110.

In the spout-attached gusset bag 101, the side edge portion of the flat surface portion 111 and the side edge portion of the side surface portion 112 are heat-sealed together to form a side edge-sealing portion 113. The side edge-sealing portion 113 of the spout-attached gusset bag 101 has high rigidity because the flat surface portion 111 and the side surface portion 112 are heat-sealed together. The side edge-sealing portion 113 serves as a support post, and thus the self-standing property of the spout-attached gusset bag 101 is improved. In addition, since the side edge-sealing portion 113 serves as a support post, the swelling of the body portion when contents are contained therein is also limited.

DOCUMENT OF RELATED ART Patent Document

-   [Patent Document 1] Japanese Patent Application, First Publication     No. H11-147547 -   [Patent Document 2] Japanese Patent Application, First Publication     No. 2000-72161 -   [Patent Document 3] Japanese Patent Application, First Publication     No. 2004-196414

SUMMARY Technical Problem

However, since the spout-attached gusset bag 101 has the side edge-sealing portion 113, a user's hand may feel discomfort when strongly squeezing the bag. That is, the side edge-sealing portion 113 projects outward of the gusset bag 110 and has high rigidity, and an end 113 a thereof is comparatively sharp. Accordingly, a user's hand may feel discomfort because the end 113 a is embedded in the hand when squeezing the bag. Particularly, in the case in which the contents are a jelly drink or the like, in general, the gusset bag 110 is squeezed by a user's hand to push out the contents when the user drinks the contents. Accordingly, it is desired to prevent a user's hand from feeling discomfort even when squeezing the gusset bag 110.

The method for preventing a user's hand from feeling discomfort when squeezing the bag includes a method of not forming the side edge-sealing portion 113 by using a cylindrical gusset bag in which all of the flat surface portions 111 and the side surface portions 112 are formed integrally with each other. However, in this method, since the side edge-sealing portion 113 serving as a support post is not formed, the self-standing property of the gusset bag may deteriorate.

An object of the present invention is to provide a gusset bag that has an improved self-standing property and can prevent a user's hand from feeling discomfort even when squeezing the gusset bag and to provide a spout-attached gusset bag in which a spout is attached to the gusset bag.

Solution to Problem

The present invention employs the following configurations to solve the above problems.

A first aspect of the present invention is a gusset bag including: a pair of flat surface portions facing each other; and a pair of side surface portions facing each other and folded inward of the gusset bag. A containing portion used to contain an object is formed using the pair of flat surface portions and the pair of side surface portions. The gusset bag has a side edge-sealing portion in which a side edge portion of a flat surface portion of the flat surface portions and a side edge portion of a side surface portion of the side surface portions are heat-sealed together, and a folded-back portion in which the entire side edge-sealing portion is folded back and affixed to the flat surface portion or the side surface portion that forms the containing portion. In addition, the peel strength of the folded-back portion is lower than the peel strength of the side edge-sealing portion.

A second aspect of the present invention is that in the gusset bag of the first aspect, the peel strength of the side edge-sealing portion is 25 N/15 mm or more, and the peel strength of the folded-back portion is 10 N/15 mm or less.

A third aspect of the present invention is that in the gusset bag of the first or second aspect, the peel strength of the side edge-sealing portion is 2.5 or more times the peel strength of the folded-back portion.

A fourth aspect of the present invention is that in the gusset bag of any one of the first to third aspects, a first flat surface portion of the pair of flat surface portions and the pair of side surface portions are formed of a first film member, and a second flat surface portion of the pair of flat surface portions is formed of a second film member. Two side edge-sealing portions are formed by heat-sealing side edge portions of the pair of side surface portions opposite to the first flat surface portion and side edge portions of the second flat surface portion together. In addition, the two side edge-sealing portions are affixed to the second flat surface portion forming the containing portion.

A fifth aspect of the present invention is that in the gusset bag of the fourth aspect, two surfaces of the second film member are capable of heat-sealing, and the two side edge-sealing portions are heat-sealed to the second flat surface portion forming the containing portion.

A sixth aspect of the present invention is that in the gusset bag of the fourth aspect, a seal layer is provided between the side edge-sealing portion and the second flat surface portion forming the containing portion in the folded-back portion.

A seventh aspect of the present invention is that in the gusset bag of any one of the fourth to sixth aspects, the first flat surface portion serves as the front surface of the gusset bag, and the second flat surface portion serves as the rear surface of the gusset bag.

A eighth aspect of the present invention is that in the gusset bag of any one of the first to seventh aspects, lower portions of the pair of flat surface portions and of the pair of side surface portions are configured to form the bottom surface of the gusset bag by being bent inward with respect to the gusset bag.

A ninth aspect of the present invention is a spout-attached gusset bag in which a spout is attached to an opening of the gusset bag according to any one of the first to eighth aspects.

Effects

A gusset bag and a spout-attached gusset bag of the present invention have an improved self-standing property and can prevent a user's hand from feeling discomfort even when squeezing the gusset bag.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front view showing an example of an embodiment of a spout-attached gusset bag of the invention.

FIG. 2 is a cross-sectional view in which the spout-attached gusset bag of FIG. 1 is cut along 2-2 line.

FIG. 3 is an enlarged cross-sectional view of the vicinity of a side edge-sealing portion of the spout-attached gusset bag of FIG. 2.

FIG. 4 is a perspective view showing an aspect in which the spout-attached gusset bag of FIG. 1 is filled with contents.

FIG. 5A is a perspective view showing a step of manufacturing the spout-attached gusset bag of FIG. 1.

FIG. 5B is a cross-sectional view showing the step of manufacturing the spout-attached gusset bag of FIG. 1.

FIG. 6A is a perspective view showing a step of manufacturing the spout-attached gusset bag of FIG. 1.

FIG. 6B is a cross-sectional view showing the step of manufacturing the spout-attached gusset bag of FIG. 1.

FIG. 7 is a perspective view showing a step of manufacturing the spout-attached gusset bag of FIG. 1.

FIG. 8 is a cross-sectional view showing the step of manufacturing the spout-attached gusset bag of FIG. 1.

FIG. 9A is a cross-sectional view of upper portions of flat surface portions showing a step of manufacturing the spout-attached gusset bag of FIG. 1.

FIG. 9B is a cross-sectional view of upper portions of side surface portions showing a step of manufacturing the spout-attached gusset bag of FIG. 1.

FIG. 9C is an enlarged view of the vicinity of an upper sealing portion of the gusset bag showing the step of manufacturing the spout-attached gusset bag of FIG. 1.

FIG. 10A is a cross-sectional view showing another form of the side edge-sealing portion of the gusset bag.

FIG. 10B is a cross-sectional view showing another form of the side edge-sealing portion of the gusset bag.

FIG. 10C is a cross-sectional view showing another form of the side edge-sealing portion of the gusset bag.

FIG. 11 is a view showing a step of manufacturing a gusset bag of another embodiment.

FIG. 12 is a cross-sectional view showing the step of manufacturing the spout-attached gusset bag of FIG. 1.

FIG. 13A is a cross-sectional view showing another embodiment of the spout-attached gusset bag of the invention.

FIG. 13B is a cross-sectional view showing another embodiment of the spout-attached gusset bag of the invention.

FIG. 13C is a cross-sectional view showing another embodiment of the spout-attached gusset bag of the invention.

FIG. 13D is a cross-sectional view showing another form of the side edge-sealing portion of the gusset bag.

FIG. 14A is a perspective view showing a step of manufacturing of another example of the spout-attached gusset bag of the invention.

FIG. 14B is a perspective view showing the step of manufacturing of another example of the spout-attached gusset bag of the invention.

FIG. 15 is a cross-sectional view showing the step of manufacturing of another example of the spout-attached gusset bag of the invention.

FIG. 16 is a front view showing another embodiment of the spout-attached gusset bag of the invention.

FIG. 17 is a cross-sectional view in which the spout-attached gusset bag of FIG. 16 is cut along 17-17 line.

FIG. 18 is an enlarged cross-sectional view of the vicinity of a side edge-sealing portion of the spout-attached gusset bag of FIG. 17.

FIG. 19 is a cross-sectional view showing a step of manufacturing the spout-attached gusset bag of FIG. 16.

FIG. 20 is a cross-sectional view showing the step of manufacturing the spout-attached gusset bag of FIG. 16.

FIG. 21 is a perspective view showing a spout-attached gusset bag of a third embodiment of the present invention and showing the front surface of the spout-attached gusset bag.

FIG. 22 is a perspective view showing the spout-attached gusset bag of the third embodiment of the present invention and showing the rear surface of the spout-attached gusset bag.

FIG. 23 is a front view of a gusset bag of the third embodiment of the present invention.

FIG. 24 is a rear view of the gusset bag of the third embodiment of the present invention.

FIG. 25 is a cross-sectional view taken along 25-25 line in FIG. 23.

FIG. 26 is an enlarged view of FIG. 25.

FIG. 27 is a cross-sectional view showing another fixing structure for a side edge-sealing portion.

FIG. 28 is a cross-sectional view showing another fixing structure for the side edge-sealing portion.

FIG. 29 is a cross-sectional view showing a gusset bag of a modification of the third embodiment of the present invention.

FIG. 30 is a perspective view showing a first application area of a sealing agent used for a manufacturing process for the spout-attached gusset bag of the third embodiment of the present invention.

FIG. 31 is a cross-sectional view taken along 31-31 line in FIG. 30.

FIG. 32 is a perspective view showing a second application area of the sealing agent used for the manufacturing process for the spout-attached gusset bag of the third embodiment of the present invention.

FIG. 33 is a cross-sectional view taken along 33-33 line in FIG. 32.

FIG. 34 is a front view showing an example of a conventional spout-attached gusset bag.

FIG. 35 is a cross-sectional view taken along 35-35 line of the spout-attached gusset bag of FIG. 34.

DESCRIPTION OF EMBODIMENTS

A gusset bag and a spout-attached gusset bag of the invention are gusset bags having the same form, except for the presence or absence of a spout. Hereinafter, as an embodiment of the gusset bag and the spout-attached gusset bag of the invention, an example of a spout-attached gusset bag having a spout will be shown and described in detail.

First Embodiment

As shown in FIG. 1, a spout-attached gusset bag 1 of this embodiment has a gusset bag 10 and a spout 20 liquid-tightly attached to the gusset bag 10.

As shown in FIGS. 1 and 2, the gusset bag 10 has a pair of flat surface portions 11, 11 facing each other, and a pair of side surface portions 12 which connect the side edges of the flat surface portions 11, 11 to each other and are facing each other. The side surface portions 12 are folded toward the inside of the gusset bag 10 by folding lines 12 a which are formed at corresponding positions to each other. Moreover, four side edge-sealing portions 13 are formed by heat-sealing the side edge portions of the flat surface portions 11 and the side edge portions of the side surface portions 12 together. In addition, an upper sealing portion 14 in which the flat surface portions 11 and the side surface portions 12 are sealed together is formed at the upper portion of the gusset bag 10, and a lower sealing portion 15 in which the inner surfaces of the flat surface portions 11 and the inner surfaces of the side surface portions 12 are heat-sealed together is formed at the lower portion of the gusset bag 10. Accordingly, the contents can be contained in the gusset bag 10.

The flat surface portions 11, 11 facing each other constitute the front surface and the rear surface of the spout-attached gusset bag 1.

The flat surface portion 11 is formed of a film member. Examples of the film member include a single-layer film and a multilayer film having a multilayer structure. In terms of adding various functions, the film member of the flat surface portion 11 is preferably a multilayer film, and more preferably a multilayer film having a heat-sealable innermost layer, a functional layer, and an outermost layer.

Examples of a film which is used as the innermost layer include an unstretched film formed of one or more selected from a group consisting of polyolefin resins such as low-density polyethylene (LDPE), medium-density polyethylene, high-density polyethylene, polypropylene (PP), and linear low-density polyethylene (LLDPE), mixed resins thereof, an ionomer resin, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid copolymer, an ethylene-acrylic acid methyl copolymer, and an ethylene-methacrylic acid copolymer. The thickness of the innermost layer is preferably in the range of 30 to 200 μm.

As a film which is used as the outermost layer, a film having high mechanical suitability and printability is preferably used. Examples thereof include films formed of synthetic resins such as polyester, polyamide, polypropylene, polycarbonate, and polyacetal. These films may be unstretched films, or stretched films stretched uniaxially or biaxially. In terms of printability, a uniaxially or biaxially oriented film is preferably used. Specific examples thereof include an oriented plastic films and the like such as biaxially oriented polyethylene terephthalate (PET), biaxially oriented polyamide (ONY), and biaxially oriented polypropylene (OPP). In addition, if necessary, synthetic paper, cellophane, paper, nonwoven cloth and the like can also be used. The thickness of the outermost layer is preferably in the range of 9 to 30 μm.

The functional layer can be appropriately selected in accordance with required functions such as gas barrier properties, mechanical toughness, flex resistance, pierce resistance, shock resistance, wear resistance, cold resistance, heat resistance, and chemical resistance.

Examples of a film which is used for the functional layer include metal foils such as aluminum, iron, copper, tin and the like, films of polyethylene terephthalate, polyamide, polyvinyl chloride, polycarbonate, polyvinyl alcohol, ethylene-vinyl acetate copolymer saponification product, and the like, films obtained by applying polyvinylidene chloride to the above films or vapor-depositing an inorganic material such as aluminum, silicon oxide, aluminum oxide, indium oxide, tin oxide, zirconium oxide, and magnesium oxide, films of polyvinylidene chloride, nonwoven cloth having heat insulating properties, and a foamed film.

The functional layer may be a single layer or two or more layers. The thickness of the functional layer may satisfy the functions which are required for the gusset bag 10, and is preferably in the range of 6 to 25 μm.

In addition, as a film which is used for the outermost layer, a vapor-deposited film having a vapor-deposited layer provided thereon may be used in place of providing the functional layer on a film member of the flat surface portion 11.

Examples of a vapor-deposited layer include inorganic materials such as aluminum, silicon oxide, aluminum oxide, indium oxide, tin oxide, zirconium oxide, magnesium oxide and the like.

Specific examples of the film member of the flat surface portion 11 include, for example, a film formed of PET (12 μm)/Al (7 μm)/ONY (15 μm)/LLDPE (60 μm) in order from the outermost layer.

The same member as the film member of the flat surface portion 11 can be used as a film member of the side surface portion 12. The material of at least the innermost layer of the film member of the side surface portion 12 is preferably the same as the material of the innermost layer of the film member of the flat surface portion 11 in terms of sealability.

The spout 20 has an extraction tube 21 which is inserted into the gusset bag 10 to extract the contents, and a cap 22 which is screwed to the upper portion of the extraction tube 21 to close the extraction port of the extraction tube 21. The spout 20 is liquid-tightly attached to the upper sealing portion 14 by heat-sealing in a state in which the extraction tube 21 is sandwiched between the upper edge portions of the flat surface portions 11, 11.

As a material of the spout 20, the material of at least a part of the extraction tube 21 which is sealed with the inner surface of the flat surface portion 11 is a synthetic resin.

Examples of a synthetic resin which forms at least the sealing portion of the extraction tube 21 of the spout 20 include a polyolefin resin, a polyamide resin, a polyester resin, a (meth) acrylic resin, a vinyl chloride resin, a vinylidene chloride resin, polyether sulfone, an ethylene-vinyl alcohol copolymer and the like. Among them, a polyolefin resin is preferably used in terms of excellent workability and low cost.

Examples of a polyolefin resin include a polyethylene-based resin such as high-density polyethylene, medium-density polyethylene, high-pressure-process low-density polyethylene, linear low-density polyethylene, and an ethylene-vinyl acetate copolymer, an olefin-based elastomer such as an ethylene-α-olefin copolymer, a polypropylene-based resin such as polypropylene, an ethylene-propylene random copolymer, and an α-olefin-propylene random copolymer, a cyclic polyolefin resin and the like. These resins may be blended to improve the performance, or may be partially cross-linked for the purpose of improvement in heat resistance and the like.

The spout 20 may be formed of a single material, or may be formed to have a multilayer structure formed of various resin layers.

In terms of sealability, the resin which forms at least the sealing portion of the extraction tube 21 of the spout 20 is preferably the same as the resin which forms the innermost layer of the flat surface portion 11.

As shown in FIGS. 2 and 3, in the spout-attached gusset bag 1 of this embodiment, a folded-back portion 13 b which is a part of the side edge-sealing portion 13 in the width direction thereof is folded back toward the side surface portion 12. Furthermore, the folded-back portion 13 b folded toward the side surface portion 12 is affixed to a base end portion of the side edge-sealing portion 13.

Accordingly, as shown in FIGS. 2 to 4, even in a state in which contents are contained in the gusset bag 10 so that the side edge-sealing portion 13 projects toward the outside of the gusset bag 10, an end portion 13 a of the side edge-sealing portion 13 with an edge which is relatively sharp faces the gusset bag 10, and does not project to the outside of the gusset bag 10. In place of the end portion 13 a, a folded line portion 13 c which is rounder than the end portion 13 a projects on the outside of the gusset bag 10.

In this manner, since the folded-back portion 13 b of the side edge-sealing portion 13 of the spout-attached gusset bag 1 is folded back and affixed as described above, the angular end portion 13 a of the side edge-sealing portion 13 does not touch a user's hand but the folded line portion 13 c which is rounder than the end portion 13 a touches the hand when the spout-attached gusset bag 1 is squeezed. Accordingly, it is possible to push out the contents by squeezing the gusset bag 10 while preventing the hand from feeling discomfort.

In addition, in the side edge-sealing portion 13, since the folded-back portion 13 b is folded back and affixed, a total of four film members, that is, the two flat surface portions 11 and the two side surface portions 12 overlap each other in the adhered portion. As a result, since the rigidity is further increased and the function as a support post is sufficiently obtained in the portion in which the folded-back portion 13 b is affixed, the spout-attached gusset bag 1 has an improved self-standing property.

The folded-back portion 13 b of the side edge-sealing portion 13 can be affixed by an adhesive. Examples of an adhesive include an adhesive in which a polyester resin is dispersed, a hot melt agent and the like. In addition, when the material of the outer surfaces of the flat surface portions 11 and the side surface portions 12 is a heat-sealable material, the folded-back portion 13 b of the side edge-sealing portion 13 may be welded by heat-sealing.

In addition, since the two flat surface portions 11, 11 and the side surface portion 12 folded toward the inside of the gusset bag 10 overlap each other at the side edge of the upper sealing portion 14, the four film members overlap each other. In this case, when the folded-back portion 13 b of the side edge-sealing portion 13 is also folded back and affixed in the upper sealing portion 14, the number of film members increases by an amount corresponding to the folded-back portion 13 at the side edge of the upper sealing portion 14, and thus the eight film members overlap each other. In this manner, when the number of film members increases at the side edge of the upper sealing portion 14, the overlapping state of the film members in the upper sealing portion 14 becomes non-uniform. In addition, when the number of overlapping film members increases at the side edge of the upper sealing portion 14, the pressure is not sufficiently applied to the vicinity of the center of the upper sealing portion 14 at the time of sealing, and thus there is concern that the sealing is not completely performed in the vicinity of the spout 20 and the contents leak.

Therefore, as shown in FIGS. 1 and 4, in the upper sealing portion 14 of the spout-attached gusset bag 1, the folded-back portion 13 b of the side edge-sealing portion 13 is preferably removed. Accordingly, the upper sealing portion 14 becomes uniform and the sealing can thus be easily and sufficiently performed, whereby the contents are easily prevented from leaking.

In the sealing of the outer surfaces of the side surface portions 12 in the upper sealing portion 14, for example, as shown in FIGS. 9B and 9C, punch holes are formed at positions facing each other in the vicinities of the side edges of the side surface portions 12 facing each other, and inner surfaces 11 a, 11 a of the flat surface portions 11, 11 are heat-sealed in the punch holes to form sealing portions 16. In addition, the outer surfaces of the side surface portions 12 in the upper sealing portion 14 may be directly adhered to each other by an adhesive, a heat-sealable film or a double-sided adhesive tape.

Examples of a method of manufacturing the gusset bag of the invention include a method (β) having the following steps (β1) to (β4).

(β1) A step of conveying two long film members (C) which form flat surface portions and a plurality of long film members (D) which are center-folded along the longitudinal direction and form side surface portions so that the plurality of center-folded film members (D) are in parallel to each other between the two film members (C), the fold lines of the center-folded film members (D) positioned at both ends are directed to the inside, and the fold lines of the film members (D) parallel to each other are alternately directed to the right and left, to heat-seal the respective side edge portions of each of the film members (D) to each of the two film members (C) along the longitudinal direction.

(β2) A step of cutting the heat-sealed film members (C) and (D) between the side edge portions, facing each other, of the two film members (D) along the longitudinal direction to obtain a plurality of cylindrical film members having the flat surface portions and the side surface portions in which four side edge-sealing portions are formed.

(β3) A step of folding back all or a part of the side edge-sealing portion in the width direction toward the flat surface portion or the side surface portion.

(β4) A step of heat-sealing and cutting the cylindrical film member along the direction perpendicular to the longitudinal direction to divide the cylindrical film member into a plurality of pieces in the longitudinal direction.

When the spout is attached, in the step (β4), the spout is attached when an upper portion of one of the plurality of pieces into which the cylindrical film member is divided is sealed.

Hereinafter, the case of the spout-attached gusset bag 1 will be taken as an example and described in detail.

Step (β1):

As shown in FIG. 5A, two long film members (C) 11B which form the pair of flat surface portions 11 facing each other and a plurality of long film members (D) 12B which are center-folded along the longitudinal direction and form the pair of side surface portions 12 facing each other are conveyed by a roller or the like. At this time, the plurality of film members (D) 12B are disposed in parallel to each other between the two film members (C) 11B. In addition, the film members (D) 12B are disposed so that the fold lines of the center-folded film member (D) 12B positioned at both ends are directed to the inside, and the fold lines of the film members (D) 12B parallel to each other are alternately directed to the right and left.

In addition, in this example, as shown in FIG. 5B, an adhesive is applied to an adhesion portion 13 d for the case in which the folded-back portion 13 b is affixed.

Next, by heat-sealing the respective side edge portions of each of the film members (D) 12B to each of the two film members (C) 11B along the longitudinal direction, heat-sealing portions 13B to be the side edge-sealing portions 13 of the spout-attached gusset bag 1 are formed.

Step (β2):

The heat-sealing portion 13B of the film members (C) 11B and (D) 12B is cut along the straight line R, that is, along the longitudinal direction between the side edge portions, facing each other, of the two film members (D) 12B to cut out a plurality of cylindrical film members having the flat surface portions 11, 11 and the side surface portions 12 in which the four side edge-sealing portions 13 are formed as shown in FIGS. 7 and 8.

In addition, at this time, in a portion corresponding to the folded-back portion 13 b of the side edge-sealing portion 13, a sealing portion 13 e is removed so that the folded-back portion 13 b is removed at the upper sealing portion 14 of the spout-attached gusset bag 1.

Step (β3):

Each folded-back portion 13 b of the side edge-sealing portion 13 in the cylindrical film member obtained in the step (β3) is folded back toward the side surface portion 12 to be affixed by the adhesive applied to the adhesion portion 13 d.

Step (β4):

With regard to the cylindrical film member, the inner surfaces of the flat surface portions 11 and the inner surface of the side surface portions 12 at a portion to be the lower sealing portion 15 are heat-sealed to each other along the straight line Y, that is, along the direction perpendicular to the longitudinal direction with a predetermined interval in the longitudinal direction of the film members (C) 11B and (D) 12B. Then, the film members (C) 11B and (D) 12B are cut along the straight line Y, that is, along the direction perpendicular to the longitudinal direction with a predetermined interval in the longitudinal direction of the film members (C) 11B and (D) 12B, and divided into a plurality of pieces in the longitudinal direction to obtain bag-shaped film members in which the lower sealing portion 15 is formed in the lower portions of the flat surface portions 11 and the side surface portions 12.

Next, in the upper portions of the flat surface portions 11 and the side surface portions 12 of the bag-shaped film member as one of the plurality of pieces into which the cylindrical film member is divided, the sealing of the inner surfaces of the flat surface portions 11 and the contact surfaces of the flat surface portion 11 and the side surface portion 12, and the attachment of the spout 20 are performed by heat-sealing. Furthermore, the outer surfaces of the side surface portions 12 are sealed together to form the upper sealing portion 14. Examples of a method of sealing the outer surfaces of the side surface portions 12 to each other in the upper sealing 14 include the following method.

As shown in FIG. 9A, punch holes 12 b, 12 b are formed to be facing each other in the vicinity of the side edge of the folded side surface portion 12 in the upper portion of the side edge-sealing portion 13, and as shown in FIGS. 9B and 9C, the inner surfaces 11 a, 11 a of the flat surface portions 11 facing each other are brought into contact with each other and heat-sealed in the portions corresponding to the punch holes 12 b, 12 b to form a sealing portion 16, whereby the outer surfaces of the side surface portions 12 are sealed together.

In addition, as another method of sealing the outer surfaces of the side surface portions 12 in the upper sealing portion 14 to each other, a method of fixing the outer surfaces of the side surface portions 12 to each other by using an adhesive, a heat-sealable film or a double-sided adhesive tape is provided as an example.

The spout-attached gusset bag 1 can be obtained by the above-described steps.

The method (β) is preferably the above-described method in terms of ease of manufacturing, but is not limited to the above-described method.

In the step (β4), any of the operation of forming the lower sealing portion 15, the operation of cutting the cylindrical film member along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, and the operation of forming the upper sealing portion 14 and attaching the spout 20 may be performed first, or the operations may be performed at the same time. For example, after the cylindrical film member was cut along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, the lower portions of the divided cylindrical film members may be sealed and the upper portions thereof may be sealed with the attached spout.

In addition, the operation of folding back and affixing the side edge-sealing portion 13 in the step (β3) is not limited to being before the step (β4). For example, after the cylindrical film member was cut along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, the side edge-sealing portions of the divided cylindrical film members may be folded back and affixed. In addition, in accordance with the used material of the film member, the side edge-sealing portion 13 may be fixed by heat-sealing without using the adhesive.

In addition, examples of a method of manufacturing the gusset bag of the invention other than the method (β) include a method (γ) having the following steps (γ1) to (γ4).

(γ1) A step of conveying two long film members (E) which form flat surface portions and a plurality of long cylindrical film members (F) which form side surface portions so that the plurality of film members (F) are in parallel to each other between the two film members (E) to heat-seal the center portions of the film members (F) and the two film members (E) along the longitudinal direction.

(γ2) A step of cutting the heat-sealing portions of the film members (E) and (F) along the longitudinal direction to obtain a cylindrical film member having the flat surface portions and the side surface portions in which four side edge-sealing portions are formed.

(γ3) A step of folding back all or a part of the side edge-sealing portion in the width direction toward the flat surface portion or the side surface portion.

(γ4) A step of heat-sealing and cutting the cylindrical film member along the direction perpendicular to the longitudinal direction to divide the cylindrical film member into a plurality of pieces in the longitudinal direction.

When the spout is attached, in the step (γ4), the spout is attached when an upper portion of one of the plurality of pieces into which the cylindrical film member is divided is sealed.

Hereinafter, the case of the spout-attached gusset bag 1 will be taken as an example and described in detail.

Step (γ1):

As shown in FIG. 6A, two long film members (E) 11A which form the pair of flat surface portions 11 facing each other and a plurality of long cylindrical film members (F) 12A which form the pair of side surface portions 12 facing each other are conveyed by a roller or the like so that the plurality of film members (F) 12A are in parallel to each other between the two film members (E) 11A. In this example, as shown in FIG. 6B, an adhesive is applied to the adhesion portion 13 d for the case in which the folded-back portion 13 b is affixed.

Next, by heat-sealing the center portions of the film members (F) 12A and the two film members (E) 11A along the longitudinal direction, heat-sealing portions 13A to be the side edge-sealing portions 13 of the spout-attached gusset bag 1 are formed. In this example, the heat-sealing portion 13A is formed so that the center portion thereof in the direction perpendicular to the longitudinal direction is not heat-sealed.

Step (γ2):

The heat-sealing portion 13A of the film members (E) 11A and (F) 12A is cut along the straight line X, that is, along the longitudinal direction at the non-heat-sealed portion of the center portion of the heat-sealing portion 13A to cut out a plurality of cylindrical film members having the flat surface portions 11, 11 and the side surface portions 12 in which the four side edge-sealing portions 13 are formed as shown in FIGS. 7 and 8.

In addition, at this time, in a portion corresponding to the folded-back portion 13 b of the side edge-sealing portion 13, the sealing portion 13 e is removed so that the folded-back portion 13 b is removed at the upper sealing portion 14 of the spout-attached gusset bag 1.

Step (γ3):

Each folded-back portion 13 b of the side edge-sealing portion 13 in the cylindrical film member obtained in the step (γ2) is folded back toward the side surface portion 12 to be affixed by the adhesive applied to the adhesion portion 13 d.

Step (γ4):

With regard to the cylindrical film member, the inner surfaces of the flat surface portions 11 and the inner surface of the side surface portions 12 at a portion to be the lower sealing portion 15 are heat-sealed to each other along the straight line Y, that is, along the direction perpendicular to the longitudinal direction with a predetermined interval in the longitudinal direction of the film members (E) 11A and (F) 12A. Then, the film members (E) 11A and (F) 12A are cut along the straight line Y, that is, along the direction perpendicular to the longitudinal direction with a predetermined interval in the longitudinal direction of the film members (E) 11A and (F) 12A, and divided into a plurality of pieces in the longitudinal direction to obtain bag-shaped film members in which the lower sealing portion 15 is formed in the lower portions of the flat surface portions 11 and the side surface portions 12.

Next, in the upper portions of the flat surface portions 11 and the side surface portions 12 of the bag-shaped film member as one of the plurality of pieces into which the cylindrical film member is divided, the sealing of the inner surfaces of the flat surface portions 11 and the contact surfaces of the flat surface portion 11 and the side surface portion 12, and the attachment of the spout 20 are performed by heat-sealing.

Furthermore, the outer surfaces of the side surface portions 12 are sealed together to form the upper sealing portion 14. The method of sealing the outer surfaces of the side surface portions 12 in the upper sealing 14 can be performed in the same manner as in the step (β4) of the method (β).

The spout-attached gusset bag 1 can be obtained by the above-described steps.

The method (γ) is preferably the above-described method in terms of ease of manufacturing, but is not limited to the above-described method.

In the step (γ4), any of the operation of forming the lower sealing portion 15, the operation of cutting the cylindrical film member along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, and the operation of forming the upper sealing portion 14 and attaching the spout 20 may be performed first, or the operations may be performed at the same time. For example, after the cylindrical film member was cut along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, the lower portions of the divided cylindrical film members may be sealed and the upper portions thereof may be sealed with the attached spout.

In addition, the operation of folding back and affixing the side edge-sealing portion 13 in the step (γ3) is not limited to being before the step (γ4). For example, after the cylindrical film member was cut along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, the side edge-sealing portions of the divided cylindrical film members may be folded back and affixed. In addition, in accordance with the used material of the film member, the side edge-sealing portion 13 may be fixed by heat-sealing without using the adhesive.

In addition, in the step (γ1), when the film members (E) 11A and (F) 12A are heat-sealed to form the heat-sealing portion 13A, the center portion of the film member (F) 12A in the width direction may not be in a non-heat-sealed state, and may be continuously heat-sealed.

In addition, in the step (γ1), together with the film members (E) 11A and (F) 12A, the same long film members center-folded along the longitudinal direction as those in the method (β) are preferably conveyed so as to be placed at both side ends of the two film members (E) 11A so that the fold lines thereof are directed to the inside, to heat-seal the side edge portions of the center-folded film members and the two film members (E) 11A. Accordingly, it is possible to make full use of both side ends of the film member (E) 11A in the manufacturing of the gusset bag.

As a method of manufacturing the spout-attached gusset bag 1, the method (β) is more preferably used than the method (γ).

In the above-described spout-attached gusset bag 1, the folded-back portion 13 b of the side edge-sealing portion 13 in which the side edge portion of the flat surface portion 11 and the side edge portion of the side surface portion 12 are heat-sealed together is folded back toward the side surface portion 12 and affixed. Accordingly, when the gusset bag 1 is squeezed by a user's hand, the end portion 13 a does not touch the hand, but the folded line portion 13 c touches the hand. Since the folded line portion 13 c is round with no edges, a user's hand is prevented from feeling discomfort even when the contents are pushed out by squeezing the gusset bag 1.

The gusset bag of this embodiment is not limited to the above-described spout-attached gusset bag 1. For example, as shown in FIG. 10A, the folded-back portion 13 b of the side edge-sealing portion 13 may be folded back toward the flat surface portion 11 and affixed thereto. In addition, as shown in FIG. 10B, the entire side edge-sealing portion 13 may be folded back toward the flat surface portion 11 and affixed to the flat surface portion 11. In addition, as shown in FIG. 10C, the entire side edge-sealing portion 13 may be folded back toward the side surface portion 12 and affixed to the side surface portion 12.

In the gusset bag of the invention, the entire side edge-sealing portion 13 is preferably folded back toward the flat surface portion 11 or the side surface portion 12.

In addition, as shown in FIGS. 10B and 10C, when the entire side edge-sealing portion 13 is folded back in the manufacture of the gusset bag by the method (γ), in place of the cutting the film members (E) 11A and (F) 12A along the straight line X, the film members are preferably cut along the straight line Z as shown in FIG. 11, that is, the film members are preferably cut so that the side edge-sealing portion 13 is further shortened.

Particularly, in the manufacturing method when the entire side edge-sealing portion 13 is folded back toward the flat surface portion 11 or the side surface portion 12, it is preferable to use a method of folding back and affixing the entire side edge-sealing portion 13 in a state in which a quadrangular prism-shaped mandrel 40 (support) is inserted into the cylindrical film member formed of the flat surface portions 11, 11 and the side surface portions 12 as shown in FIG. 12. When using this method, it is possible to easily fold back and affix the side edge-sealing portion 13, and thus the spout-attached gusset bag can be more efficiently manufactured.

In addition, in the spout-attached gusset bag of this embodiment, two or more of the four kinds of folding-back methods illustrated in FIGS. 3 and 10A to 10C may be used in combination for the four side edge-sealing portions 13. That is, in the gusset bag of this embodiment, a form of folding back the entire side edge-sealing portion 13 and a form of folding back a part of the side edge-sealing portion 13 may be used in combination, and a form of folding back the side edge-sealing portion 13 toward the flat surface portion 11 and a form of folding back the side edge-sealing portion 13 toward the side surface portion 12 may be used in combination.

In addition, the number of the side edge-sealing portions 13 is not limited to four, and may be less than four. A spout-attached gusset bag in which the number of the side edge-sealing portions 13 is not four is preferably a spout-attached gusset bag in which one flat surface portion and a pair of side surface portions are formed of one film member, and the side edge portions of the side surface portions formed of the above film member and the side edge portions of the other flat surface portion are heat-sealed together to form the two side edge-sealing portions.

Specifically, as shown in FIG. 13A, the spout-attached gusset bag preferably has a gusset bag 10A in which the flat surface portion 11 to be the front surface of the bag and the pair of side surface portions 12 facing each other are formed of one integrated film member, the side edge portions of the side surface portions 12 of the above film member and the side edge portions of the other flat surface portion 11 are heat-sealed together to form the two side edge-sealing portions 13, and a part of the side edge-sealing portion 13 is folded back toward the side surface portion 12 and affixed thereto. In this gusset bag 10A, the entire side edge-sealing portion 13 may be folded back, the side edge-sealing portion 13 may be folded back toward the flat surface portion 11, or these may be used in combination.

In addition, as shown in FIG. 13B, the spout-attached gusset bag particularly preferably has a gusset bag 10B in which the flat surface portion 11 to be the front surface of the bag and the pair of side surface portions 12 facing each other are formed of one integrated film member, the side edge portions of the side surface portions 12 of the above film member and the side edge portions of the other flat surface portion 11 are heat-sealed together to form the two side edge-sealing portions 13, and the entire side edge-sealing portion 13 is folded back toward the front surface portion 11 which forms the rear surface and affixed. The spout-attached gusset bag having the gusset bag 10B has no side edge-sealing portion in the front surface, and thus a user's hand is prevented from feeling discomfort particularly when squeezing the bag from the front surface, and the appearance is also excellent. In addition, since the side edge-sealing portions are formed of the flat surface portion which form the rear surface and the side surface portions at both sides of the flat surface portion, an improved self-standing property can be obtained due to the side edge-sealing portion functioning as a support post, and the swelling of the body portion when containing contents is also suppressed.

In addition, as shown in FIG. 13C, the spout-attached gusset bag of the invention may be a gusset bag 10C in which one side surface portion and a pair of flat surface portions facing each other are integrally formed of one film member, the two side edge-sealing portions 13 by heat-sealing are formed only in the side of the other side surface portion, and the side edge-sealing portion 13 is folded back toward the flat surface portion or the side surface portion and affixed thereto.

In addition, when the flat surface portion 11 and the side surface portion 12 are formed of a film member integrated at any portion, as shown in FIG. 13D, the side edge-sealing portion 13 may be formed by heat-sealing a portion corresponding to the side edge portion of the flat surface portion 11 and a portion corresponding to the side edge portion of the side surface portion 12 to each other, and all or a part of the side edge-sealing portion 13 may be folded back toward the flat surface portion 11 or the side surface portion 12, and affixed. Accordingly, it is possible to prevent a user's hand from feeling discomfort when the gusset bag is squeezed and to improve the self-standing property of the spout-attached gusset bag by forming the side edge-sealing portion to be a support post.

In addition, the folded-back portion 13 b of the side edge-sealing portion 13 does not have to be necessarily affixed to the flat surface portion 11 or the side surface portion 12 if the folded-back state can be stably maintained.

Examples of a method of manufacturing the gusset bag having the same form as those of the gusset bags 10A and 10B include a method (α) having the following steps (α1) to (α4).

(α1) A step of conveying a long film member (A) which forms one flat surface portion and a pair of side surface portions with a long film member (B) which forms the other flat surface portion in a state in which the long film member (A) is folded so that a plurality of the one flat surface portion and the pair of side surface portions are formed in parallel to each other along the longitudinal direction, to heat-seal the portion between the neighboring side surface portions of the film member (A) to the film member (B) along the longitudinal direction and heat-seal each of the portions at the side ends from the side surface portions positioned at both ends of the film member (A) to the film member (B) along the longitudinal direction.

(α2) A step of cutting the heat-sealing portion of the film members (A) and (B) along the longitudinal direction to obtain a plurality of cylindrical film members having the flat surface portions and the side surface portions in which two side edge-sealing portions are formed.

(α3) A step of folding back all or a part of the side edge-sealing portion in the width direction toward the flat surface portion or the side surface portion.

(α4) A step of heat-sealing and cutting the cylindrical film member along the direction perpendicular to the longitudinal direction to divide the cylindrical film member into a plurality of pieces in the longitudinal direction.

When the spout is attached, in the step (α4), the spout is attached when an upper portion of one of the plurality of pieces into which the cylindrical film member is divided is sealed.

Hereinafter, the case of a spout-attached gusset bag having the gusset bag 10B will be taken as an example and described in detail.

Step (α1):

As shown in FIG. 14A, a long film member (A) 17 which forms one flat surface portion 11 and the pair of side surface portions 12 are conveyed by a roller or the like with a long film member (B) 18 which forms the other flat surface portion 11 in a state in which the film member (A) 17 is folded so that a plurality of the one flat surface portion 11 and the pair of side surface portions 12 are formed in parallel to each other along the longitudinal direction. In addition, in this example, as shown in FIG. 14B, an adhesive is applied to the adhesion portion 13 d for the case in which the folded-back portion is affixed.

Next, the portion between the neighboring side surface portions 12 of the film member (A) 17 and the film member (B) 18 are heat-sealed together along the longitudinal direction, and each of the portions at the side ends from the side surface portions positioned at both ends of the film member (A) 17 and the film member (B) 18 are heat-sealed together along the longitudinal direction, whereby the heat-sealing portions 13C to be the side edge-sealing portions 13 are formed.

Step (α2):

The heat-sealing portion 13C of the film members (A) 17 and (B) 18 is cut along the straight line Q, that is, along the longitudinal direction at the center portion of the heat-sealing portion 13C to cut out a plurality of cylindrical film members having the flat surface portions 11, 11 and the side surface portions 12 in which the two side edge-sealing portions 13 are formed as shown in FIG. 15.

In addition, if necessary, in the same manner as in the method (β), a part of a portion corresponding to the side edge-sealing portion 13 is removed so that no folded-back portion remains in the upper sealing portion of the spout-attached gusset bag.

Step (α3):

Each of the entire side edge-sealing portions 13 of the cylindrical film member obtained in the step (α2) is folded back toward the flat surface portion 11 to be affixed by the adhesive applied to the adhesion portion 13 d.

Step (α4):

In the same manner as in the step (β4) of the method (β), the heat-sealing and cutting are performed along the direction perpendicular to the longitudinal direction and the division into a plurality of pieces is performed in the longitudinal direction, whereby bag-shaped film members are obtained in which the lower sealing portion 15 is formed. Then, in the same manner as in the step (β4) of the method (β), the sealing of the upper portions of the flat surface portions 11 and the side surface portions 12 and the attachment of the spout 20 are performed.

The method (α) is preferably the above-described method in terms of ease of manufacturing, but is not limited to the above-described method.

In the step (α4), any one of the operation of forming the lower sealing portion 15, the operation of cutting the cylindrical film member along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, and the operation of forming the upper sealing portion 14 and attaching the spout 20 may be performed first, or the operations may be performed at the same time. For example, after the cylindrical film member was cut along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, the lower portions of the divided cylindrical film members may be sealed and the upper portions thereof may be sealed with the attached spout.

In addition, the operation of folding back and affixing the side edge-sealing portion 13 in the step (α3) is not limited to being before the step (α4). For example, after the cylindrical film member was cut along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, the side edge-sealing portions of the divided cylindrical film members may be folded back and affixed. In addition, in accordance with the used material of the film member, the side edge-sealing portion 13 may be fixed by heat-sealing without using the adhesive.

Second Embodiment

Next, another embodiment of the spout-attached gusset bag of the invention will be described. In this embodiment, the same parts as those in the spout-attached gusset bag 1 will be denoted by the same reference signs, and descriptions thereof will be omitted.

As shown in FIG. 16, a spout-attached gusset bag 2 of this embodiment has a gusset bag 30 and a spout 20 liquid-tightly attached to the gusset bag 30.

As shown in FIGS. 16 and 17, the gusset bag 30 has a pair of flat surface portions 31, 31 facing each other, and a pair of side surface portions 32, 32 which connect the side edges of the flat surface portions 31, 31 to each other and are facing each other. The side surface portions 32, 32 are folded toward the inside of the gusset bag 30 by folding lines 32 a which are formed at corresponding positions to each other. Moreover, four side edge-sealing portions 33 are formed by heat-sealing the side edge portions of the flat surface portions 31 and the side edge portions of the side surface portions 32 together. In addition, an upper sealing portion 34 in which the flat surface portions 31 and the side surface portions 32 are put together and sealed is formed at the upper portion of the gusset bag 30, and a lower sealing portion 35 in which the inner surfaces of the flat surface portions 31 and the inner surface of the side surface portions 32 are heat-sealed together is formed at the lower portion of the gusset bag 30. Accordingly, the contents can be contained in the gusset bag 30.

For the film members of the flat surface portion 31 and the side surface portion 32, it is possible to use the same material as the film members of the flat surface portion 11 and the side surface portion 12 of the spout-attached gusset bag 1, and a preferred aspect regarding the film member is similar. That is, the spout-attached gusset bag 2 is the same as the spout-attached gusset bag 1, other than the form of the side edge-sealing portion 33.

As shown in FIGS. 17 and 18, the side edge-sealing portion 33 of the spout-attached gusset bag 2 has an unsealed portion 33 b which is not heat-sealed along the vertical direction in the middle of the side edge-sealing portion 33 in the width direction thereof. A tip end portion (folded-back portion 33 c) of the side edge-sealing portion 33 is folded back toward the side surface portion 32 along the unsealed portion 33 b, and affixed to a base end portion of the side edge-sealing portion 33. That is, in order from the base end of the side edge-sealing portion 33 toward the tip end, a sealing portion 33 a which is heat-sealed, the unsealed portion 33 b which is not heat-sealed, and the folded-back portion 33 c which his heat-sealed are provided.

In the spout-attached gusset bag 2, the tip end of a portion projecting to the outside from the gusset bag 30 of the side edge-sealing portion 33 is the unsealed portion 33 b. Since the unsealed portion 33 b is not heat-sealed, the unsealed portion 33 b has lower rigidity and is softer than the folded line portion 13 c of the side edge-sealing portion 13 of the spout-attached gusset bag 1.

In addition, in the spout-attached gusset bag 2, since the sealing portion 33 a and the folded-back portion 33 c are heat-sealed together, these portions sufficiently function as a support post, and thus the gusset bag 2 has an improved self-standing property.

The spout-attached gusset bag 2 is manufactured in the same manner as in the manufacturing of the spout-attached gusset bag 1 by the method (β) or (γ), except for the form of the heat-sealing portion which is formed in the step (β2) or (γ2) and the folding-back of the side edge-sealing portion in the step (β3) or (γ3). When the method (γ) is used, for example, the following method is exemplified.

Step (γ1):

As shown in FIG. 6A, two long film members (E) 31A which form the pair of flat surface portions 31 facing each other and a plurality of long cylindrical film members (F) 32A which form the pair of side surface portions 32 facing each other are conveyed by a roller or the like so that the plurality of film members (E) 32A are in parallel to each other between the film members (E) 31A. In addition, in this example, as shown in FIG. 19, an adhesive is applied to an adhesion portion 33 d for the case in which the folded-back portion 33 c is affixed.

By heat-sealing the center portions of the film members (F) 32A and the film members (E) 31A along the longitudinal direction, heat-sealing portions to be the side edge-sealing portions 33 are formed. The heat-sealing portions are formed in order of a sealing portion 33A which is heat-sealed, an unsealed portion 33B which is not heat-sealed, a sealing portion 33C which is heat-sealed, an unsealed portion 33B which is not heat-sealed, and a sealing portion 33A which is heat-sealed, in the direction perpendicular to the longitudinal direction.

Step (γ2):

The heat-sealing portion of the film members (C) 31A and (D) 32A is cut along the straight line P, that is, along the longitudinal direction at the center of the film member 32A in the direction perpendicular to the longitudinal direction to cut out a plurality of cylindrical film members having the flat surface portions 31, 31 and the side surface portions 32, 32 in which the four side edge-sealing portions 33 are formed as shown in FIG. 20.

In addition, as in the case of manufacturing the spout-attached gusset bag 1, a part of the folded-back portion 33 c is removed so that the folded-back portion 33 c does not remain in a portion corresponding to the upper sealing portion 34 of the spout-attached gusset bag 2.

Step (γ3):

Each folded-back portion 33 c of the side edge-sealing portions 33 in the cylindrical film members obtained in the step (γ2) is folded back toward the side surface portion 32 along the unsealed portion 33 b to affix the folded-back portion 33 c by the adhesive applied to the adhesion portion 33 d.

Step (γ4):

As in the case of manufacturing the spout-attached gusset bag 1, with regard to the cylindrical film member, the inner surfaces of the flat surface portions 31 and the inner surface of the side surface portions 32 at a portion to be the lower sealing portion 35 are heat-sealed to each other along the direction perpendicular to the longitudinal direction with a predetermined interval in the longitudinal direction, and the above portion is cut along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, whereby bag-shaped film members in which the lower sealing portion 35 is formed in the lower portions of the flat surface portions 31 and the side surface portions 32 are obtained.

Next, in the upper portions of the flat surface portions 31 and the side surface portions 32 of the bag-shaped film member as one of the plurality of pieces into which the cylindrical film member is divided, the sealing of the inner surfaces of the flat surface portions 31 and the contact portions of the flat surface portion 31 and the side surface portion 32, and the attachment of the spout 20 are performed by heat-sealing. Furthermore, the outer surfaces of the side surface portions 32 are sealed together to form the upper sealing portion 34. Examples of a method of sealing the outer surfaces of the side surface portions 32 to each other in the upper sealing 34 include a method including: forming punch holes facing each other in the side surface portions 32 at the upper portions of the side edge-sealing portions 33; and bringing the inner surfaces of the flat surface portions 31 into contact with each other in the punch holes to heat-seal the inner surfaces to each other as in the case of manufacturing the spout-attached gusset bag 1. In addition, a method of fixing the outer surfaces of the side surface portions 32 to each other by using an adhesive, a heat-sealable film or a double-sided adhesive tape may also be used.

The spout-attached gusset bag 2 can be obtained by the above-described steps.

The method of manufacturing the spout-attached gusset bag 2 is also not limited to the above-described method as in the case of manufacturing the spout-attached gusset bag 1.

Any of the operation in the step (β4), the operation of forming the lower sealing portion 35, the operation of cutting the cylindrical film member along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, and the operation of forming the upper sealing portion 34 and attaching the spout 20 may be performed first, or the operations may be performed at the same time. For example, after the cylindrical film member was cut along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, the lower portions of the divided cylindrical film members may be sealed and the upper portions thereof may be sealed with the attached spout.

In addition, the operation of folding back and affixing the folded back portion 33 c of the side edge-sealing portion 33 in the step (β3) is not limited to being before the step (β4). For example, after the cylindrical film member was cut along the direction perpendicular to the longitudinal direction to be divided into a plurality of pieces in the longitudinal direction, the folded-back portions 33 c of the side edge-sealing portions 33 of the divided cylindrical film members may be folded back and affixed. In addition, in accordance with the used material of the film member, the side edge-sealing portion 13 may be fixed by heat-sealing without using the adhesive.

In addition, also in the case of manufacturing the spout-attached gusset bag 2, in the step (γ1), together with the film members (E) 31A and (F) 32A, the long film members center-folded along the longitudinal direction are preferably conveyed so as to be placed at both side ends of the two film members (E) 31A so that the fold lines thereof are directed to the inside, to heat-seal the side edge portions of the center-folded film members and the two film members (E) 31A. Accordingly, it is possible to make full use of both side ends of the film member (E) 31A in the manufacturing of the gusset bag. In forming of the heat-sealing of the side edge portions of the center-folded film members and the two film members (E) 31A, a sealing portion which is heat-sealed, an unsealed portion which is not heat-sealed, and a sealing portion which is heat-sealed are formed in this order, in the direction perpendicular to the longitudinal direction.

In the above-described spout-attached gusset bag 2, the folded-back portion 33 c of the side edge-sealing portion 33 in which the side edge portion of the flat surface portion 31 and the side edge portion of the side surface portion 32 are heat-sealed together is folded back toward the side surface portion 32 along the unsealed portion 33 b and affixed thereto. Accordingly, when the spout-attached gusset bag 2 is squeezed by a user's hand, the round unsealed portion 33 b which is not heat-sealed and has low rigidity touches the hand. Therefore, it is possible to push out the contents by squeezing the spout-attached gusset bag 2 while preventing the hand from feeling discomfort.

The spout-attached gusset bag of this embodiment is not limited to the above-described spout-attached gusset member 2. For example, the folded-back portion 33 c may be folded back toward the flat surface portion 11 and affixed thereto. In addition, in the four side edge-sealing portions 33, the side edge-sealing portions in which the folded-back portion 33 c is folded back toward the flat surface portion 11 and the side edge-sealing portions in which the folded-back portion 33 c is folded back toward the side surface portion 12 may be used in combination.

In addition, the number of the side edge-sealing portions 33 is not limited to four, and may be less than four. For example, a film member in which one side surface portion is formed integrally with a pair of flat surface portions facing each other may be used to form the side edge-sealing portions 33 by heat-sealing only in the side of the other side surface portion, and the folded-back portion 33 c may be folded back along the unsealed portion 33 b and affixed.

In addition, when a film member in which the flat surface portion 31 and the side surface portion 32 are formed integrally with each other at any portion is used, the side edge-sealing portion 33 may be formed by heat-sealing a portion corresponding to the side edge portion of the flat surface portion 31 and a portion corresponding to the side edge portion of the side surface portion 32 to each other, and the folded-back portion 33 c of the side edge-sealing portion 33 may be folded back toward the flat surface portion 31 or the side surface portion 32 along the unsealed portion 33 b, and affixed. Accordingly, it is possible to prevent a user's hand from feeling discomfort when the gusset bag is squeezed and improve the self-standing property of the gusset bag by forming the side edge-sealing portion to be a support post.

In addition, the spout-attached gusset bag of the invention may be a spout-attached gusset bag having a gusset bag in which the folding-back of the side edge-sealing portion described in the first embodiment and the folding-back of the side edge-sealing portion described in the second embodiment are used in combination.

In addition, the gusset bag of the invention is a bag which is the same as the above-described spout-attached gusset bag, except that the gusset bag of the invention has no spout. In this gusset bag, a notch or a cutoff line to open the bag may be formed.

Third Embodiment

Next, a third embodiment of the spout-attached gusset bag of the present invention is described. A component of this embodiment, which is approximately the same as that of the first embodiment, is attached with the same reference sign as that of the first embodiment, and duplicate descriptions may be omitted.

FIG. 21 is a perspective view showing a spout-attached gusset bag 3 of the third embodiment of the present invention and showing the front surface of the spout-attached gusset bag 3. FIG. 22 is a perspective view showing the spout-attached gusset bag 3 of the third embodiment of the present invention and showing the rear surface of the spout-attached gusset bag 3. FIGS. 21 and 22 show the spout-attached gusset bag 3 filled with liquid or semi-liquid (sol or gel) contents (an object) such as jelly drink, and the spout-attached gusset bag 3 has an approximately rectangular parallelepiped shape. That is, the four corners of the spout-attached gusset bag 3 in plan view project outward.

The spout-attached gusset bag 3 includes a gusset bag 50 and a spout 20 liquid-tightly attached to the gusset bag 50.

The gusset bag 50 includes a pair of flat surface portions 51 and 52 facing each other and a pair of side surface portions 53 facing each other and folded inward of the gusset bag 50. Two side edges of each side surface portion 53 connect with side edges of the flat surface portions 51 and 52. The flat surface portion 52 (a second flat surface portion) of the gusset bag 50 of this embodiment is provided with two side edge-sealing portions 54 described below, and the flat surface portion 52 serves as the rear surface of the gusset bag 50, and the flat surface portion 51 (a first flat surface portion) provided with no side edge-sealing portion serves as the front surface of the gusset bag 50.

FIG. 23 is a front view of the gusset bag 50 of the third embodiment of the present invention. FIG. 24 is a rear view of the gusset bag 50 of the third embodiment of the present invention. FIG. 25 is a cross-sectional view taken along 25-25 line in FIG. 23. FIGS. 23 to 25 show the gusset bag 50 that is not attached with the spout 20 and show a state before an object is filled in the gusset bag 50. Hereinafter, the upper part of FIGS. 23 and 24 may be referred to as the upper part of the gusset bag 50, the lower part of FIGS. 23 and 24 may be referred to as the lower part of the gusset bag 50, the up-and-down direction of FIGS. 23 and 24 may be referred to as the up-and-down direction of the gusset bag 50, and the left-and-right direction of FIGS. 23 and 24 may be referred to as the width direction of the gusset bag 50 (or the flat surface portion 51 or 52). In addition, the upper end of the gusset bag 50 shown in FIGS. 23 to 25 is not heat-sealed and thus serves as an opening 50 a through which the inside and the outside of the gusset bag 50 communicate with each other. The spout 20 is liquid-tightly attached to the opening 50 a of the gusset bag 50, whereby the spout-attached gusset bag 3 is manufactured.

As shown in FIG. 25, each side surface portion 53 is bent at a folding line 53 a and is folded inward of the gusset bag 50. Since the two side edges of each side surface portion 53 are connected to side edges of the flat surface portions 51 and 52, the gusset bag 50 is provided with a containing portion 55 that is enclosed by the pair of flat surface portions 51 and 52 and the pair of side surface portions 53 and is used to contain an object. That is, the containing portion 55 is formed using the pair of flat surface portions 51 and 52 and the pair of side surface portions 53.

As shown in FIGS. 23 and 24, each of the flat surface portions 51 and 52 is formed into an approximate rectangle, and the width of each lower part of the flat surface portions 51 and 52 gradually decreases toward the lower end thereof. A depressed part 56 is provided in the vicinity of each of the two corners of the upper part of the gusset bag 50. The flat surface portion 51, the side surface portion 53 and the flat surface portion 52 are joined together through heat-sealing, ultrasonic-sealing, an adhesive or the like at the two corners of the upper part of the gusset bag 50, and the corner is pressed by a die or the like having a projection at the time they are joined, whereby the depressed part 56 is formed. In addition, in order to join the flat surface portion 51, the side surface portion 53 and the flat surface portion 52 to each other at the corners, the structure using the sealing portion 16 of the first embodiment may be applied to the gusset bag 50 (refer to FIGS. 9B and 9C). That is, a through-hole, notch or the like may be provided in the side surface portion 53, and the inner surfaces of the flat surface portions 51 and 52 may be directly heat-sealed through the through-hole, notch or the like. If the depressed part 56 is provided in the gusset bag 50, the joint strength of each of the two corners of the upper part of the gusset bag 50 can be increased. However, the depressed part 56 is not essential for the gusset bag of the present invention, and if a sufficient joint strength of the corner is secured through joining using heat-sealing, ultrasonic-sealing, an adhesive or the like, the depressed part 56 does not have to be provided therein.

The lower part of the gusset bag 50 is provided with a first lower sealing portion 57 and second lower sealing portions 58. The first lower sealing portion 57 is provided in the lower end of the gusset bag 50 between the pair of side surface portions 53 and is formed by directly heat-sealing the inner surfaces of the flat surface portions 51 and 52. The second lower sealing portions 58 are provided in two parts between which the first lower sealing portion 57 is disposed in the width direction of the flat surface portions 51 and 52 and are formed by heat-sealing the inner surfaces of the flat surface portion 51 and the side surface portion 53 and by heat-sealing the inner surfaces of the flat surface portion 52 and the side surface portion 53. The first lower sealing portion 57 and the second lower sealing portions 58 are provided in the lower part of the gusset bag 50, and the opening 50 a of the upper part of the gusset bag 50 is sealed, whereby the containing portion 55 is provided with a liquid-tight space used for filling an object therein. In the gusset bag 50, lower portions of the pair of flat surface portions 51 and 52 and of the pair of side surface portions 53 are configured to form the bottom surface (the under surface) of the gusset bag 50 by being bent inward with respect to the gusset bag 50 (by being bent toward the central axis of the spout-attached gusset bag 3 extending in the up-and-down direction and passing through the spout 20). The gusset bag 50, namely the spout-attached gusset bag 3, can independently stand in a state where the bottom surface contacts a supporting surface.

As shown in FIG. 25, in the gusset bag 50 of this embodiment, side edge portions of the pair of side surface portions 53 opposite to the flat surface portion 51 and side edge portions of the flat surface portion 52 are heat-sealed together, whereby the two side edge-sealing portions 54 are formed. That is, the gusset bag 50 has the two side edge-sealing portions 54. In addition, the gusset bag 50 has a folded-back portion 59 in which the entire side edge-sealing portion 54 is folded back and affixed through heat-sealing to the flat surface portion 52 that forms the containing portion 55. That is, the gusset bag 50 has the two folded-back portions 59. As shown in FIG. 24, the side edge-sealing portions 54 of this embodiment extend from the upper end to the lower end of the gusset bag 50 (the flat surface portion 52). However, a configuration may be adopted in which the side edge-sealing portion 54 is not provided in at least one of the upper part and the lower part of the gusset bag 50 similarly to the first embodiment. Although the side edge-sealing portion 54 of this embodiment has a constant width, the side edge-sealing portion 54 may have different widths. The depressed parts 56 are provided on the side edge-sealing portions 54.

As shown in FIG. 25, in the gusset bag 50 of this embodiment, the flat surface portion 51 and the pair of side surface portions 53 are formed of a first film member 60 continuous on the entire area of the portion 51 and the portions 53, and the flat surface portion 52 is formed of a second film member 61. The first film member 60 is bent at two folded line portions 60 a, whereby the flat surface portion 51 and the two side surface portions 53 are partitioned. Thus, the two folded line portions 60 a are positioned in two of the four corners of the gusset bag 50 in plan view. In this embodiment, a side edge portion of the flat surface portion 51 and a side edge portion of the side surface portion 53 are not heat-sealed at a position corresponding to the folded line portion 60 a. Various film members shown in the first embodiment can be employed for the film members 60 and 61, that is, a single-layer film or a multilayer film having a multilayer structure can be used therefor, and multilayer films are used for the film members 60 and 61 of this embodiment.

Two surfaces of the second film member 61 of this embodiment are capable of heat-sealing. That is, the second film member 61 is a multilayer film that includes an innermost layer forming the inner surface of the gusset bag 50, an outermost layer forming the outer surface of the gusset bag 50 and a functional layer arranged therebetween, and each of the innermost layer and the outermost layer has heat-sealability. The film used for the innermost layer includes, for example, an unstretched film of liner low-density polyethylene (LLDPE). In addition, an unstretched film shown in the first embodiment may be used for the innermost layer of the second film member 61 of this embodiment and is formed of one or more selected from a group consisting of polyolefin resins such as low-density polyethylene (LDPE), medium-density polyethylene, high-density polyethylene, and polypropylene (PP), mixed resins thereof, an ionomer resin, an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid copolymer, an ethylene-acrylic acid methyl copolymer, and an ethylene-methacrylic acid copolymer. The thickness of the innermost layer is, for example, 30 to 200 μm. The film used for the outermost layer includes, for example, a biaxially oriented film of heat-sealable polyethylene terephthalate (HSPET). In addition, the above-described film that can be employed for the innermost layer of the second film member 61 of this embodiment may be used for the outermost layer of the second film member 61, and in this case, the thickness of the outermost layer may be less than that of the innermost layer. The thickness of the outermost layer is, for example, 9 to 30 μm. The functional layer may include only one layer or may include two layers or more. The second film member 61 of this embodiment includes two functional layers, one of the functional layers is an aluminum foil (Al) laminated on the outermost layer, and the other of the functional layers is a biaxially oriented film of polyamide (NY) laminated on the innermost layer. The thickness of each functional layer is, for example, 6 to 25 μm. That is, the second film member 61 is a film in which HSPET/Al/NY/LLDPE are piled in order from the outermost layer. In contrast, in the first film member 60 of this embodiment, only the innermost layer thereof is capable of heat-sealing. In addition, the thickness of each layer of the film members 60 and 61 can be appropriately adjusted.

FIG. 26 is an enlarged view of FIG. 25. As shown in FIG. 26, in this embodiment, the entire side edge-sealing portion 54 is heat-sealed on the outer surface of the flat surface portion 52 that forms the containing portion 55. That is, unlike the first embodiment, the side edge-sealing portion 54 of this embodiment is not bent at any folded line portions positioned within the side edge-sealing portion 54 such that part of the side edge-sealing portion 54 overlaps other part of the side edge-sealing portion 54. Since two surfaces of the second film member 61 forming the flat surface portion 52 are capable of heat-sealing, the side edge-sealing portion 54 is folded back to the flat surface portion 52, the surface of part of the second film member 61 forming the side edge-sealing portion 54 overlaps the surface of other part of the second film member 61 forming the containing portion 55, and heat is applied to the parts in this state, whereby the side edge-sealing portion 54 can be affixed to the flat surface portion 52 forming the containing portion 55. The side edge-sealing portion 54 is folded back at a folded line portion 59 a to the flat surface portion 52. That is, the side edge-sealing portions 54 is folded back such that the end 54 a of the side edge-sealing portion 54 approaches the center of the flat surface portion 52 in the width direction. In a state where the side edge-sealing portion 54 is affixed to the flat surface portion 52, the end 54 a of the side edge-sealing portion 54 is disposed in a position closer to the center of the flat surface portion 52 in the width direction than the folded line portion 59 a. Since the gusset bag 50 includes the two side edge-sealing portions 54, two folded line portions 59 a are provided therein and are positioned in two of the four corners of the gusset bag 50 in plan view. Thus, the four corners of the gusset bag 50 in plan view are configured of the two folded line portions 59 a and the two folded line portions 60 a.

Since the side edge-sealing portion 54 is formed by heat-sealing the film members 60 and 61 together, the side edge-sealing portion 54 has a higher rigidity than that of each of the first and second film members 60 and 61 that are not heat-sealed. Accordingly, when the side edge-sealing portion 54 is folded back to the flat surface portion 52, the side edge-sealing portion 54 is not substantially bent, the first and second film members 60 and 61 that are not heat-sealed are bent at the folded line portion 59 a, and thus the side edge-sealing portion 54 is folded back to the flat surface portion 52. In this case, since the folded line portion 59 a is positioned in the first and second film members 60 and 61 that are not heat-sealed, the flexibility of the folded line portion 59 a (the corner of the gusset bag 50) can be improved compared to a case where a folded line portion is positioned within a side edge-sealing portion (a case where the folded line portion, at which the side edge-sealing portion is bent, is positioned at the corner of a gusset bag).

Two surfaces of the second film member 61 of this embodiment have heat-sealability, and the side edge-sealing portion 54 is affixed to the flat surface portion 52 using the heat-sealability of the second film member 61, but the present invention is not limited to this configuration. Only the innermost layer of the second film member 61 may have heat-sealability, and the side edge-sealing portion 54 may be heat-sealed onto the flat surface portion 52 through a sealing agent (a heat-sealing agent, namely an adhesive or the like having heat-sealability). A liquid sealing agent is applied to or sprayed on a portion to be fixed and is dried or a sheet-shaped sealing agent is attached to a portion to be fixed, and thereafter heat is applied to the sealing agent, whereby the sealing agent has adhesive force. The sealing agent includes, for example, an agent that is formed of a thermoplastic resin and has adhesive force by melting the resin through application of heat and an agent that has adhesive force through activation by application of heat. In addition, a sealing agent may be used that has adhesive force by overlapping part of the sealing agent provided on a portion to be fixed with other part of the sealing agent provided on the portion to be fixed and by heating the parts.

In a case where the side edge-sealing portion 54 is affixed to the flat surface portion 52 using the sealing agent, it is sufficient that the outermost layer of the second film member 61 is a film capable of being adhered using such a sealing agent. The outermost layer is, for example, an unstretched or uniaxially or biaxially stretched film formed of a synthetic resin such as polyester, polyamide, polypropylene, polycarbonate and polyacetal. In a case where a biaxially stretched film is used, the outermost film is, for example, a biaxially stretched plastic film formed of polyethylene terephthalate (PET), polyamide (ONY), polypropylene (OPP) or the like. Synthetic paper, cellophane, paper, nonwoven cloth or the like can be used for the outermost layer. In these cases, the thickness of the outermost layer is also, for example, 9 to 30 μm.

FIG. 27 is a cross-sectional view showing another fixing structure for the side edge-sealing portion 54. FIG. 27 shows the same portion as a portion of the gusset bag 50 shown in FIG. 26. As shown in FIG. 27, in this fixing structure, a seal layer 63 (a heat-seal layer, an adhesive layer) is provided between the side edge-sealing portion 54 in the folded-back portion 59 and the flat surface portion 52 forming the containing portion 55. The side edge-sealing portion 54 is affixed to the flat surface portion 52 through the seal layer 63, in other words, the seal layer 63 affixes the side edge-sealing portion 54 to the flat surface portion 52. The seal layer 63 is a layer obtained by heating the above-described sealing agent and changing the properties thereof. In this embodiment, the edge 63 a of the seal layer 63 close to the center of the flat surface portion 52 in the width direction is disposed in the same position as the end 54 a of the side edge-sealing portion 54 close to the center of the flat surface portion 52 in the width direction. In addition, the edge 63 a of the seal layer 63 may be positioned to be closer to the center of the flat surface portion 52 in the width direction than the end 54 a of the side edge-sealing portion 54 or may be positioned to be closer to the folded line portion 59 a of the folded-back portion 59 than the end 54 a. In addition, in this embodiment, although the edge 63 b of the seal layer 63 close to the folded line portion 59 a contacts the outer surface (the surface facing the seal layer 63) of a folded line portion of the second film member 61, the present invention is not limited to this configuration, and a gap may be formed between the edge 63 b of the seal layer 63 and the outer surface of the folded line portion of the second film member 61.

In the gusset bag 50 of this embodiment, the peel strength (the heat-seal strength, the adhesive strength) of the folded-back portion 59 is lower than the peel strength (the heat-seal strength, the adhesive strength) of the side edge-sealing portion 54. The peel strength of the present invention is a force required for peeling two film pieces joined together from each other by pulling the two film pieces from each other, and the width of each film piece in a direction orthogonal to the pulling direction is 15 mm. The peel strength of the side edge-sealing portion 54 is a peel strength between the flat surface portion 52 and the side surface portion 53 that configure the side edge-sealing portion 54 (namely, a peel strength between the first and second film members 60 and 61 that configure the side edge-sealing portion 54). The peel strength of the folded-back portion 59 is a peel strength between the side edge-sealing portion 54 and the flat surface portion 52 forming the containing portion 55 (namely, a peel strength between part of the second film member 61 forming the side edge-sealing portion 54 and other part of the second film member 61 forming the containing portion 55).

For example, the peel strength of the side edge-sealing portion 54 is 25 N/15 mm or more, and it is preferable that the peel strength thereof be 50 N/15 mm or more. It is sufficient that the side edge-sealing portion 54 has a peel strength capable of holding the contents inside the spout-attached gusset bag 3 even when, for example, a user's hand squeezes the spout-attached gusset bag 3. The peel strength of the folded-back portion 59 is 10 N/15 mm or less in each of a case where two surfaces of the second film member 61 have heat-sealability and a case where the side edge-sealing portion 54 is affixed to the flat surface portion 52 through the seal layer 63. It is preferable that the peel strength of the folded-back portion 59 be about 2 to 10 N/15 mm, and it is further preferable that the peel strength thereof be about 5 to 10 N/15 mm. It is sufficient that the folded-back portion 59 is affixed to the flat surface portion 52 such that the folded-back portion 59 is prevented from being easily peeled from the flat surface portion 52 even when, for example, a user's hand squeezes the spout-attached gusset bag 3 and thereby a force is added to the folded-back portion 59 or to part around the folded-back portion 59. That is, the peel strength of the side edge-sealing portion 54 is 2.5 or more times the peel strength of the folded-back portion 59.

In the spout-attached gusset bag 3 of this embodiment, when a user's hand squeezes the containing portion 55 of the gusset bag 50, the object filled therein can also be pushed out through the spout 20. At this time, the end 54 a of the side edge-sealing portion 54 is disposed in a position closer to the center of the flat surface portion 52 in the width direction than the folded line portion 59 a so as to head for the center of the flat surface portion 52. Therefore, it is possible to prevent a user's hand from contacting the comparatively sharp end 54 a at the time the hand squeezes the gusset bag 50. In addition, the folded line portion 59 a, which is positioned at the corner of the containing portion 55 of the gusset bag 50 in plan view, is provided in the first and second film members 60 and 61 that are not heat-sealed. Therefore, the flexibility of the folded line portion 59 a that a user's hand contacts at the time the hand squeezes the gusset bag 50 can be improved compared to a case where a folded line portion at which a side edge-sealing portion is bent is positioned at the corner of a gusset bag in plan view, the folded line portion 59 a can flexibly deform in accordance with grasp by a user, and thus it is possible to decrease discomfort that the user's hand receives.

Since the side edge-sealing portion 54 is a seal portion that secures the liquid-tightness of the containing portion 55, a high seal strength is required therefor. In contrast, the heat seal of the folded-back portion 59 to the flat surface portion 52 does not relate to the liquid-tightness of the containing portion 55, and accordingly, in the gusset bag 50 of this embodiment, the peel strength of the folded-back portion 59 is set to be lower than that of the side edge-sealing portion 54. Therefore, the rigidity of the fixed portion of the folded-back portion 59, namely the rigidity of the fixed portion of the side edge-sealing portion 54 to the flat surface portion 52, can be reduced, and thus the flexibility of the folded-back portion 59 can be improved. Consequently, the folded line portion 59 a can flexibly deform in accordance with grasp by a user, and it is possible to prevent a force from concentrating at part of the user's hand and to decrease discomfort that the user's hand receives.

In the spout-attached gusset bag 3 of this embodiment, the flat surface portion 51 serving as the front surface of the gusset bag and the pair of side surface portions 53 are formed of the first film member 60 continuous on the entire area of the portion 51 and the portions 53, and the flat surface portion 52 serving as the rear surface of the gusset bag is formed of the second film member 61. In addition, side edge portions (side edge portions of the first film member 60) of the pair of side surface portions 53 opposite to the flat surface portion 51 and side edge portions (side edge portions of the second film member 61) of the flat surface portion 52 are heat-sealed together to form two side edge-sealing portions 54. Therefore, no side edge-sealing portion is provided on the front side of the gusset bag, and thus a user's hand can be appropriately prevented from feeling discomfort when squeezing the gusset bag from the front side.

If the flat surface portion 51 and the pair of side surface portions 53 are formed of different film members, it is difficult to form a continuous pattern or the like on the surfaces of these portions because print or the like is performed on each of the film members. In contrast, in this embodiment, since the flat surface portion 51 serving as the front surface of the gusset bag and the pair of side surface portions 53 are formed of one first film member 60 continuous on the entire area of the portion 51 and the portions 53, a continuous pattern or the like can be easily formed on the surfaces (the surface of the first film member 60) of these portions. Accordingly, the gusset bag can have a good appearance to become an attractive product, and the appeal thereof to consumers can be improved.

In this embodiment, since the flat surface portion 51 and the pair of side surface portions 53 are formed of one first film member 60 continuous on the entire area of the portion 51 and the portions 53, the amount of used film members can be reduced compared to a case where a flat surface portion and a pair of side surface portions are formed of different film members. Accordingly, the utilization efficiency of space in the production site can be improved, and the transportation cost thereof and the emission amount of CO₂ gas can be reduced.

It may be difficult for a gusset bag having no side edge-sealing portion to obtain a sufficient self-standing property, and particularly, this tendency may become remarkable when a spout is attached to the upper part of the gusset bag. However, since the spout-attached gusset bag 3 of this embodiment has two side edge-sealing portions 54 on the rear side thereof, the side edge-sealing portions 54 serve as posts, whereby the spout-attached gusset bag 3 can have a sufficient self-standing property, and swelling of the body portion thereof can be limited.

In the spout-attached gusset bag 3 of this embodiment, the entire two side edge-sealing portions 54 are folded back and affixed to the flat surface portion 52, and thus the side edge-sealing portions 54 do not project outward with respect to the gusset bag in plan view. Therefore, a user's hand can be appropriately prevented from feeling discomfort when squeezing the gusset bag. In addition, since the side edge-sealing portions 54 do not project outward in this embodiment, the occupied space by a spout-attached gusset bag 3 becomes less than that of a conventional gusset bag (refer to FIGS. 34 and 35) having a side edge-sealing portion projecting outward in plan view even if the capacities of these bags are the same. Accordingly, when spout-attached gusset bags 3 are packed into a transport box or the like or are displayed on a store shelf, the total occupied space by the spout-attached gusset bags 3 can be reduced.

Although the side edge-sealing portion 54 of this embodiment is affixed to the flat surface portion 52 forming the containing portion 55, the present invention is not limited to this configuration, and the side edge-sealing portion 54 may be affixed to the side surface portion 53 forming the containing portion 55. FIG. 28 is a cross-sectional view showing another fixing structure for the side edge-sealing portion 54. FIG. 28 shows the same portion as a portion of the gusset bag 50 shown in FIG. 26. As shown in FIG. 28, the side edge-sealing portion 54 is folded back and affixed through heat-sealing to the side surface portion 53 forming the containing portion 55. In order to heat-seal the side edge-sealing portion 54 to the side surface portion 53, a configuration may be adopted in which two surfaces of the first film member 60 forming the side surface portion 53 have heat-sealability, or another configuration may be adopted in which only the innermost layer of the first film member 60 has heat-sealability and the side edge-sealing portion 54 is heat-sealed to the side surface portion 53 using a sealing agent.

However, when the two side edge-sealing portions 54 are not folded back to the side surface portions 53 but are folded back to the flat surface portion 52 as shown in this embodiment, it is possible to obtain the following effects. Since the side edge-sealing portions 54 cannot be seen from the front side of the gusset bag, the displayed spout-attached gusset bag 3 can have a good appearance, and the appeal thereof to consumers can be improved. In addition, as shown in FIG. 22, since the two side edge-sealing portions 54 are folded back and affixed to the flat surface portion 52, when a bottom surface used for standing the gusset bag is formed therein, a lower part of the side edge-sealing portion 54 is bent in a direction crossing the surface of the side edge-sealing portion 54. Accordingly, the lower part of the side edge-sealing portion 54 can be appropriately bent without projecting downward with respect to the gusset bag, the bent lower part of the side edge-sealing portion 54 does not disturb self-standing of the gusset bag, and thus an improved self-standing property thereof can be obtained. In contrast, if a side edge-sealing portion is folded back and affixed to a side surface portion, when a bottom surface used for standing the gusset bag is formed therein, it is necessary to bend a lower part of the side edge-sealing portion in a direction parallel to the surface of the side edge-sealing portion. Accordingly, it may be difficult to appropriately bend the lower part of the side edge-sealing portion. Thus, in the spout-attached gusset bag 3 of this embodiment, since the side edge-sealing portions 54 are folded back and affixed to the flat surface portion 52, an improved self-standing property can be easily and appropriately obtained compared to a case where the side edge-sealing portion is folded back and affixed to the side surface portion.

Although the gusset bag 50 of this embodiment is formed of the first and second film members 60 and 61, a gusset bag may be formed of four film members and may be provided with four side edge-sealing portions and four folded-back portions similarly to the first embodiment. In this case, the peel strength of the folded-back portion can also be set to be lower than that of the side edge-sealing portion. The side edge-sealing portion can be affixed through heat-sealing to the flat surface portion or the side surface portion that forms the containing portion. Positions to which the side edge-sealing portions are folded back may be different, for example, the side edge-sealing portions on the front side of the gusset bag may be affixed to the side surface portions, and the side edge-sealing portions on the rear side of the gusset bag may be affixed to the flat surface portion (a second flat surface portion).

In the gusset bag 50 of this embodiment, the flat surface portion 51 and the pair of side surface portions 53 are formed of the first film member 60, and the flat surface portion 52 is formed of the second film member 61. However, the flat surface portion 51, one of the pair of side surface portions 53, and the flat surface portion 52 may be formed of a first film member continuous on the entire area of the portion 51, the one of the portions 53 and the portion 52, and the other of the pair of side surface portions 53 may be formed of a second film member (refer to FIG. 13C). In addition, the flat surface portion 51 and one of the pair of side surface portions 53 may be formed of a first film member continuous on the entire area of the portion 51 and the one of the portions 53, and the flat surface portion 52 and the other of the pair of side surface portions 53 may be formed of a second film member continuous on the entire area of the portion 52 and the other of the portions 53.

In the gusset bag 50 of this embodiment, the flat surface portion 51 and the pair of side surface portions 53 are formed of the first film member 60 continuous on the entire area of the portion 51 and the portions 53, the flat surface portion 51 and the two side surface portions 53 are partitioned by the folded line portions 60 a, and a position corresponding to the folded line portion 60 a is provided with no side edge-sealing portion. However, for example, in order to further improve the self-standing property of the gusset bag, the position corresponding to the folded line portion 60 a may be provided with a side edge-sealing portion (refer to FIG. 13D). FIG. 29 is a cross-sectional view showing a gusset bag 50A of a modification of this embodiment. As shown in FIG. 29, although in the gusset bag 50A, the flat surface portion 51 and the pair of side surface portions 53 are formed of the first film member 60 continuous on the entire area of the portion 51 and the portions 53, a side edge-sealing portion 64 is formed by heat-sealing a side edge portion of the flat surface portion 51 and a side edge portion of the side surface portion 53 together, and a folded-back portion 65 is formed in which the entire side edge-sealing portion 64 is folded back and affixed through heat-sealing to the side surface portion 53 forming the containing portion 55. The side edge-sealing portion 64 is formed by heat-sealing two portions of the inner surface of the first film member 60 together. The gusset bag 50A has the two side edge-sealing portions 64 and the two folded-back portions 65. The folded-back portion 65 is folded back at the folded line portion 60 a. The peel strength of the folded-back portion 65 is set to be lower than the peel strength of the side edge-sealing portion 64. In order to heat-seal the folded-back portion 65 to the side surface portion 53, two surfaces of the first film member 60 may be capable of heat-sealing, or a sealing agent may be used therefor. The side edge-sealing portion 64 may be folded back and affixed through heat-sealing to the flat surface portion 51. The numbers and positions of the folded-back portions 59 formed by folding back the side edge-sealing portions 54 and the folded-back portions 65 formed by folding back the side edge-sealing portions 64 may be appropriately changed, and it is sufficient that the gusset bag 50 of this embodiment is provided with the folded-back portion formed of at least one side edge-sealing portion.

Next, a manufacturing method for the gusset bag 50 and the spout-attached gusset bag 3 of this embodiment is described.

In a case where two surfaces of the second film member 61 of this embodiment are capable of heat-sealing, the method (α) shown in FIGS. 14A, 14B and 15 of the first embodiment can be used for manufacturing the gusset bag 50 and the spout-attached gusset bag 3. In addition, a method using the mandrel 40 shown in FIG. 12 may be adopted in order to heat-seal and affix the side edge-sealing portion 54 to the flat surface portion 52.

In contrast, in a case where a sealing agent is used for heat-sealing and affixing the side edge-sealing portion 54 to the flat surface portion 52, since only the innermost layer of the second film member 61 is capable of heat-sealing, a step (hereinafter, merely referred to as an applying step) in which the sealing agent is applied to, sprayed on or attached to the outer surface (the outer surface of the outermost layer) of the second film member 61 is added to the method (α). In addition, even if the sealing agent is used, a method using the mandrel 40 shown in FIG. 12 may be adopted in order to heat-seal and affix the side edge-sealing portion 54 to the flat surface portion 52.

The sealing agent has to be applied to the gusset bag 50 before the side edge-sealing portion 54 is heat-sealed to the flat surface portion 52. Accordingly, the sealing agent may be applied to the outer surface of the second film member 61 before the step (α1) of the method (α), for example, at the manufacturing step for or the printing step for the second film member 61. The sealing agent may be applied to the outer surface of the second film member 61 between the step (α1) and the step (α2) of the method (α), that is, the sealing agent may be applied to the outer surface of the second film member 61 (corresponding to the film member 18 shown in FIG. 14B) being in the state shown in FIG. 14B. The sealing agent may be applied to the outer surface of the second film member 61 between the step (α2) and the step (α3) of the method (α), that is, the sealing agent may be applied to the outer surface of the second film member 61 (corresponding to the film member on the lower side of FIG. 15) being in the state shown in FIG. 15.

When the sealing agent is applied to the outer surface of the second film member 61, the sealing agent may be applied to the entire outer surface thereof. In addition, the sealing agent may be applied to only an area required for heat-sealing the side edge-sealing portion 54 to the flat surface portion 52, and in this case, the application amount of the sealing agent can be reduced, and thus the manufacturing cost can be decreased.

In a case where the sealing agent is applied to only an area required for heat-sealing, the sealing agent may be applied to the entire surface or part of the side edge-sealing portion 54 or may be applied to part of the flat surface portion 52 forming the containing portion 55. FIG. 30 is a perspective view showing a first application area of the sealing agent used for a manufacturing process for the spout-attached gusset bag 3 of the third embodiment of the present invention. FIG. 31 is a cross-sectional view taken along 31-31 line in FIG. 30. FIG. 32 is a perspective view showing a second application area of the sealing agent used for the manufacturing process for the spout-attached gusset bag 3 of the third embodiment of the present invention. FIG. 33 is a cross-sectional view taken along 33-33 line in FIG. 32. In addition, each of FIGS. 30 to 33 shows one tubular member formed of the first and second film members 60 and 61 for the sake of convenience, and the second film member 61 is shown to be positioned in the upper part of these drawings. FIGS. 30 to 33 show that the sealing agent is applied to the second film member 61 between the step (α2) and the step (α3). However, in a case where the applying of the sealing agent is performed before the step (α2), the sealing agent is applied to part of the second film member 61 before the second film member 61 is joined to the first film member 60 or is applied to part of the second film member 61 (18) shown in FIG. 14B.

As shown in FIGS. 30 and 31, a sealing agent 71 extends parallel to the extending direction of the side edge-sealing portion 54 and is applied to an area from the same position as the end Ma of the side edge-sealing portion 54 in the width direction (the left-and-right direction of FIG. 30) to a position closer to the end 54 a than a folded line portion 59 b at which the side edge-sealing portion 54 is folded back. That is, a gap is formed between the sealing agent 71 and the folded line portion 59 b. In addition, if it is possible to ignore an effect of the applied sealing agent 71 on the folding back of the side edge-sealing portion 54, the sealing agent 71 may be disposed so as to contact the folded line portion 59 b. Furthermore, the sealing agent 71 may be applied to an area closer to the folded line portion 59 b than the end 54 a of the side edge-sealing portion 54, and a gap is formed between the end 54 a and the sealing agent 71. In the first application area shown in FIGS. 30 and 31, since the sealing agent 71 is applied to the side edge-sealing portion 54, even if the width of the side edge-sealing portion 54 or the position of the folded-back side edge-sealing portion 54 with respect to the flat surface portion 52 in the width direction slightly changes, the side edge-sealing portion 54 can be appropriately affixed to the flat surface portion 52. In addition, since the sealing agent 71 is applied to the same position as the end 54 a of the side edge-sealing portion 54, the end 54 a of the side edge-sealing portion 54 can be reliably fixed to the flat surface portion 52 when the side edge-sealing portion 54 is affixed through heat-sealing to the flat surface portion 52, and it is possible to prevent the end 54 a from peeling from the flat surface portion 52.

As shown in FIGS. 32 and 33, a sealing agent 72 extends parallel to the extending direction of the side edge-sealing portion 54 and is applied to an area closer to the center of the flat surface portion 52 in the width direction than the folded line portion 59 b at which the side edge-sealing portion 54 is folded back. The width (the width in the direction orthogonal to the above extending direction and parallel to the surface of the flat surface portion 52, the width in the left-and-right direction of FIG. 32) of the sealing agent 72 is greater than the width of the side edge-sealing portion 54. A gap is formed between the sealing agent 72 and the folded line portion 59 b. In addition, if it is possible to ignore an effect of the applied sealing agent 72 on the folding back of the side edge-sealing portion 54, the sealing agent 72 may be disposed so as to contact the folded line portion 59 b. Furthermore, the sealing agent 72 may be applied such that the width of the sealing agent 72 is less than that of the side edge-sealing portion 54 and the edge of the sealing agent 72 close to the center of the flat surface portion 52 in the width direction is positioned to be closer to the folded line portion 59 b than the end 54 a of the folded-back side edge-sealing portion 54. In the second application area shown in FIGS. 32 and 33, since the width of the sealing agent 72 applied to the flat surface portion 52 is greater than that of the side edge-sealing portion 54, even if the width of the side edge-sealing portion 54 or the position of the folded-back side edge-sealing portion 54 with respect to the flat surface portion 52 in the width direction slightly changes, the folded-back side edge-sealing portion 54 can be positioned within the sealing agent 72 and thus can be appropriately affixed to the flat surface portion 52. In other words, the width or position of the sealing agent 72 may be set such that the folded-back side edge-sealing portion 54 is positioned within the sealing agent 72 even if the width of the side edge-sealing portion 54 or the position of the side edge-sealing portion 54 folded back to the flat surface portion 52 in the width direction changes. Since the folded-back side edge-sealing portion 54 can be positioned within the sealing agent 72, the end 54 a of the side edge-sealing portion 54 is reliably fixed to the flat surface portion 52 when the side edge-sealing portion 54 is affixed through heat-sealing to the flat surface portion 52, and it is possible to prevent the end 54 a from peeling from the flat surface portion 52.

In addition, in order to obtain this effect, in a case where the width of the sealing agent 72 is less than that of the side edge-sealing portions 54, the width (the distance) from the folded line portion 59 b to the edge of the sealing agent 72 close to the center of the flat surface portion 52 in the width direction may be greater than the width of the side edge-sealing portion 54.

If a melted resin of the sealing agent during heat-sealing has to be prevented from adhering to a sealing bar or the like used for heat-sealing, a material capable of preventing adhesion of the above melted resin may be used for the surface of the sealing bar, a sheet or the like formed of a material capable of preventing adhesion of the above melted resin may be arranged between the gusset bag and the sealing bar during heat-sealing, or the area of the gusset bag that is pressed by the sealing bar may be limited.

In a case where a sealing agent is used that has adhesive force by overlapping part of the sealing agent provided on a portion to be fixed with other part of the sealing agent provided on the portion to be fixed and by heating the parts, for example, the sealing agent is applied to both of the first application area shown in FIGS. 30 and 31 and the second application area shown in FIGS. 32 and 33.

The application area of the above-described sealing agent can be appropriately adjusted in accordance with the properties of or the intended use of the sealing agent.

In this embodiment, a film member whose two surfaces have heat-sealability or a sealing agent having heat-sealability is used for affixing the side edge-sealing portion 54 to the flat surface portion 52 or the side surface portion 53 that forms the containing portion 55. However, it is possible to use an adhesive, a double-sided adhesive tape or the like having no heat-sealability for affixing a side edge-sealing portion to a flat surface portion or a side surface portion and for forming a folded-back portion. In this case, the peal strength of the folded-back portion can also be lower than that of the side edge-sealing portion similarly to this embodiment. In the case where an adhesive or the like having no heat-sealability is used, the adhesive or the like is applied to the outer surface of a film member before the side edge-sealing portion is folded back, namely between the step (α2) and the step (α3) of the method (α) shown in FIGS. 30 to 33.

INDUSTRIAL APPLICABILITY

According to the present invention, it is possible to provide a gusset bag that has an improved self-standing property and can prevent a user's hand from feeling discomfort even when squeezing the gusset bag and to provide a spout-attached gusset bag in which a spout is attached to the gusset bag. 

1. A gusset bag comprising: a pair of flat surface portions facing each other; and a pair of side surface portions facing each other and folded inward of the gusset bag, wherein a containing portion used to contain an object is formed using the pair of flat surface portions and the pair of side surface portions, wherein the gusset bag has a side edge-sealing portion in which a side edge portion of a flat surface portion of the flat surface portions and a side edge portion of a side surface portion of the side surface portions are heat-sealed together, and a folded-back portion in which the entire side edge-sealing portion is folded back and affixed to the flat surface portion or the side surface portion that forms the containing portion, and wherein the peel strength of the folded-back portion is lower than the peel strength of the side edge-sealing portion.
 2. The gusset bag according to claim 1, wherein the peel strength of the side edge-sealing portion is 25 N/15 mm or more, and wherein the peel strength of the folded-back portion is 10 N/15 mm or less.
 3. The gusset bag according to claim 1, wherein the peel strength of the side edge-sealing portion is 2.5 or more times the peel strength of the folded-back portion.
 4. The gusset bag according to claim 1, wherein a first flat surface portion of the pair of flat surface portions and the pair of side surface portions are formed of a first film member, wherein a second flat surface portion of the pair of flat surface portions is formed of a second film member, wherein two side edge-sealing portions are formed by heat-sealing side edge portions of the pair of side surface portions opposite to the first flat surface portion and side edge portions of the second flat surface portion together, and wherein the two side edge-sealing portions are affixed to the second flat surface portion forming the containing portion.
 5. The gusset bag according to claim 4, wherein two surfaces of the second film member are capable of heat-sealing, and wherein the two side edge-sealing portions are heat-sealed to the second flat surface portion forming the containing portion.
 6. The gusset bag according to claim 4, wherein a seal layer is provided between the side edge-sealing portion and the second flat surface portion forming the containing portion in the folded-back portion.
 7. The gusset bag according to claim 4, wherein the first flat surface portion serves as the front surface of the gusset bag, and the second flat surface portion serves as the rear surface of the gusset bag.
 8. The gusset bag according to claim 1, wherein lower portions of the pair of flat surface portions and of the pair of side surface portions are configured to form the bottom surface of the gusset bag by being bent inward with respect to the gusset bag.
 9. A spout-attached gusset bag in which a spout is attached to an opening of the gusset bag according to claim
 1. 